As we've discussed previously, anyone using fertility drugs cannot rely on a home pregancy test (HPT) result.

Trigger injections like Pregnyl or Ovidrel are a synthetic form of hCG. Home pregnancy tests are designed to detect hCG. It takes 5 to 7 days for the effects of Pregnyl or Ovidrel to wear off. So if you use an HPT during this period you will most likely get a false result.

A blood test, on the other hand, will look at beta hCG levels and progesterone levels. High levels of both indicate a corpus luteum (the crater left on the ovary from the follicle that released an ovum) is producing enough of both these hormones to sustain a pregnancy.

However, if Pregnyl has been used in luteal support (the 14 days after ovulation), this will impact the hCG levels. For example, the beta hCG reading could be over 45, but if the progesterone levels read some crazy number like 1.4, this is called a chemical pregnancy. An ultrasound would most likely prove there is no egg sack and no embryo, although AF usually comes well before that happens.

Hope this answers your question.